Method for manufacturing rotor, rotor, drive apparatus, and end plate

This application is based upon and claims the benefit of priority from Japanese patent application No. 2022-181611, filed on Nov. 14, 2022, the disclosure of which is incorporated herein in its entirety by reference.

The present disclosure relates to a method for manufacturing a rotor, a rotor, a drive apparatus, and an end plate.

For example, a rotor has a configuration in which a rotor core is held by an end plate in order to fix a plurality of electromagnetic steel sheets that form the rotor core. For example, in Japanese Unexamined Patent Application Publication No. 2012-125034, an end plate is provided so as to hold a rotor core, a magnet is inserted into a magnet insertion hole of the rotor core via a magnet insertion hole formed in one end plate, and then the magnet insertion hole provided in the end plate is filled up with a non-magnetic material such as resin. This rotor is thus manufactured.

The applicants have found the following problem. A general rotor is configured in such a way that a magnet is fixed to a rotor core by resin injected into a magnet insertion hole of the rotor core. Therefore, there is a problem that the magnet inserted into the magnet insertion hole of the rotor core is surrounded by resin and therefore the magnet cannot be efficiently cooled down.

The present disclosure has been made in view of the above problem, and provides a method for manufacturing a rotor, a rotor, a drive apparatus, and an end plate capable of efficiently cooling down a magnet inserted into a magnet insertion hole of a rotor core.

A method for manufacturing a rotor according to one aspect of the present disclosure is a method for manufacturing a rotor in which a rotor core including electromagnetic steel sheets laminated to each other is held by a first end plate and a second end plate, the method including: fixing the first end plate in which a slit is formed to one end part of the rotor core in an axial direction and causing a magnet insertion hole of the rotor core and the slit of the first end plate to be continuous; fixing the second end plate to another end part of the rotor core in the axial direction; and holding the magnet inserted into the magnet insertion hole of the rotor core by a convex part that is formed in a position of the first end plate overlapping the magnet in the axial direction of the rotor core and the second end plate and fixing the magnet therein.

The aforementioned method for manufacturing the rotor may include: bending, when the magnet is inserted into the magnet insertion hole of the rotor core, a cover part that is disposed inside the slit having a C shape in the first end plate and forming a magnet insertion hole in the first end plate, and causing the magnet insertion hole of the rotor core to be exposed and inserting the magnet into the magnet insertion hole of the rotor core via the magnet insertion hole of the first end plate; and bending back, when the magnet is fixed, the cover part of the first end plate so as to cover the magnet insertion hole of the rotor with the cover part, thereby causing the convex part formed in the cover part of the first end plate to contact the magnet.

In the aforementioned method for manufacturing the rotor, the cover part of the first end plate may be bent or bent back by a preset bend line, and the convex part may be formed so as to cross over the bend line.

The aforementioned method for manufacturing the rotor may include fixing the first end plate in which the convex part is formed in advance to one end part of the rotor core in the axial direction.

The aforementioned method for manufacturing the rotor may include: measuring a value of a measurement parameter that is set in advance when a voltage is applied between the first end plate and the second end plate after the magnet is fixed; and adjusting a bent-back amount of the cover part of the first end plate in such a way that the value of the measurement parameter becomes smaller than a preset threshold.

A rotor according to one aspect of the present disclosure is a rotor in which a rotor core including electromagnetic steel sheets laminated to each other is held by a first end plate and a second end plate, in which the first end plate includes: a slit that is continuous with a magnet insertion hole of the rotor core; and a convex part that is formed in a position of the first end plate overlapping a magnet inserted into the magnet insertion hole of the rotor core in an axial direction of the rotor core and is protruded toward the magnet, the magnet is held by the convex part of the first end plate and the second end plate and fixed therein, and a gap is formed between the magnet insertion part of the rotor core and the magnet.

In the aforementioned rotor, the slit may have a C shape and the convex part may be disposed so as to cross over a line that connects end parts of the slit on a side of an opening.

In the aforementioned rotor, the second end plate may include a slit that is continuous with the magnet insertion hole of the rotor core.

In the aforementioned rotor, the second end plate includes a convex part that is formed in a position of the second end plate overlapping the magnet in an axial direction of the rotor core and is protruded toward the magnet, and the magnet is held by the convex part of the first end plate and the convex part of the second end plate and fixed therein.

A drive apparatus according to one aspect of the present disclosure includes: a motor including the above rotor; a housing that houses the motor; and a cooling medium supplied to the inside of the housing.

An end plate according to one aspect of the present disclosure is an end plate that is used to hold a rotor core including electromagnetic steel sheets laminated to each other, the end plate including: a slit that is continuous with a magnet insertion hole of the rotor core in a state in which the end plate is fixed to an end part of the rotor core in an axial direction.

The aforementioned end plate may include a convex part that is formed in a position of the end plate overlapping the magnet inserted into the magnet insertion hole of the rotor core in the axial direction of the rotor core in a state in which the end plate is fixed to the end part of the rotor core in the axial direction and is protruded toward the magnet.

According to the present disclosure, it is possible to achieve a method for manufacturing a rotor, a rotor, a drive apparatus, and an end plate capable of efficiently cooling down a magnet inserted into a magnet insertion hole of a rotor core.

The above and other objects, features and advantages of the present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present disclosure.

Hereinafter, with reference to the drawings, a specific embodiment to which the present disclosure is applied will be described in detail. However, the present disclosure is not limited to the following embodiment. Further, for the sake of clarification of the description, the following description will be given using a three-dimensional (XYZ) coordinate system, and the following descriptions and the drawings are simplified as appropriate.

First, a configuration of a drive apparatus according to this embodiment will be described.is a diagram showing a configuration of a drive apparatus according to this embodiment. As shown in, a drive apparatusaccording to this embodiment includes a motor, a housing, and a cooling medium.

As shown in, the motorincludes a statorand a rotor. The statorincludes a stator corein which electromagnetic steel sheets having a substantially annular shape that are substantially parallel to an XZ plane are laminated in a Y-axis direction, and a coilwound onto the stator core.

is a cross-sectional view showing the rotor according to this embodiment. As shown in, the rotorincludes a rotor core, a shaft, a magnet, a first end plate, and a second end plate. As shown in, the rotoris inserted into a through-holeformed in the stator coreof the stator.

As shown in, the rotor coreis formed of electromagnetic steel sheetsthat are laminated in the Y-axis direction, the electromagnetic steel sheetshaving a substantially annular shape that are substantially parallel to the XZ plane. The rotor coreincludes a through-holepenetrating substantially the center of the rotor corein the Y-axis direction, and magnet insertion holesthat are disposed in the circumferential direction of the rotor corewith gaps therebetween and penetrate the rotor corein the Y-axis direction.

As shown in, the shaftis extended in the Y-axis direction and is fixed to the rotor corein a state in which the shaftis inserted into the through-holeof the rotor core. The magnetis extended in the Y-axis direction and is inserted into the magnet insertion holeof the rotor core. At this time, a gap G (see) is formed between the circumferential surface of the magnetand the circumferential surface of the magnet insertion holeof the rotor core. Inand so on, the gap G is exaggerated.

As shown in, for example, the first end plateis fixed to an end part of the rotor coreon the positive Y-axis side by means such as welding. However, the means for fixing the first end plateto the end part of the rotor coreon the positive Y-axis side is not particularly limited. For example, the first end platemay be fixed to the end part of the rotor coreon the positive Y-axis side by a claw or the like formed in the first end plate.

The first end plate, which is formed of, for example, an electromagnetic steel sheet, has, as a basic form, a substantially annular shape when seen from a Z-axis direction.is a diagram showing a state in which the magnet is covered with a cover part of the first end plate in the rotor according to this embodiment when seen from the positive Y-axis side.is a cross-sectional view showing a state in which the magnet is covered with the cover part of the first end plate in the rotor according to this embodiment.is a diagram showing a convex part of the first end plate.

As shown in, the first end plateincludes a slit, a cover part, and a convex part. As shown in, the slitis provided so as to surround the magnet insertion holeof the rotor coreexcept for a part of the magnet insertion holeof the rotor core(e.g., radially outer end of the rotor corein the magnet insertion hole), and has, for example, a substantially C shape when seen from the Y-axis direction.

As shown in, the whole area of the magnet insertion holeof the rotor coreis disposed in a first area ARsurrounded by an outer edge OEof the slitand a line Lthat connects end partsof the sliton a side of an opening when seen from the Y-axis direction. Therefore, the end partsof the sliton the side of the opening are disposed on the radially outer side of the rotor corewith respect to the radially outer end of the rotor corein the magnet insertion holeof the rotor core.

The C shape is not limited to a rectangular shape, and may include a curved shape or a polygonal shape. In summary, the C shape allows the whole area of the magnet insertion holeof the rotor coreto be disposed in the first area ARof the slitwhen seen from the Y-axis direction. At this time, as shown in, the magnet insertion holeof the rotor coreand the slitof the first end platemay partially overlap each other when seen from the Y-axis direction.

As shown in, the cover partis formed in an inner area of the slit. That is, the cover partforms a second area ARsurrounded by an inner periphery IE of the slitand the line Lthat connects the end partsof the sliton the side of the opening. The cover part, which has, for example, a substantially rectangular shape when seen from the Y-axis direction, covers at least a part of the magnet.

The cover partcan be bent and bent back by a bending line Lin such a way that the whole end of the magnet insertion holeof the rotor coreon the positive Y-axis side can be exposed. The bending line Lmay be arranged on the line Lthat connects the end partsof the sliton the side of the opening, as shown in, for example,.

However, it is sufficient that the bending line Lbe arranged in such a way that the whole end of the magnet insertion holeof the rotor coreon the positive Y-axis side can be exposed when the cover partis bent. Note that the bending line Lmay be arranged, for example, on the surface of the first end plateon the negative Y-axis side.

As shown in, the convex partis protruded toward the negative Y-axis from the cover part. The end part of the convex parton the negative Y-axis side touches the end part of the magneton the positive Y-axis side. The convex partmay be formed, for example, by pressing a part of the first end platetoward the negative Y-axis side. However, the convex partmay be formed of a material other than that of the first end plateand fixed to the end part of the first end plateon the negative Y-axis side.

As shown in, the convex partmay be disposed so as to cross over the bending line L. Accordingly, springback when the cover partis bent back may be reduced. At this time, as shown in, when the convex partinterferes with the rotor core, a concave partthat allows the convex partto escape may be formed in the rotor core.

As shown in, for example, the second end plateis fixed to the end part of the rotor coreon the negative Y-axis side by means such as welding, and the magnetis held between the convex partof the first end plateand the second end plateand fixed therein.

Note that the means for fixing the second end plateto the end part of the rotor coreon the negative Y-axis side is not limited, and the second end platemay be fixed to the end part of the rotor coreon the negative Y-axis side by, for example, a claw or the like formed in the second end plate.

The second end platemay be formed of, for example, an electromagnetic steel sheet, and has, as a basic form, a substantially annular shape when seen from the Z-axis direction. The second end platemay have a configuration substantially the same as that of the first end plate.

is a diagram showing a state in which the magnet is covered with the cover part of the second end plate in the rotor according to this embodiment when seen from the negative Y-axis side.is a cross-sectional view showing a state in which the magnet is covered with the cover part of the second end plate in the rotor according to this embodiment.

That is, while the detailed descriptions will be omitted, as shown in, the second end plateincludes a slitthat is arranged so as to surround the magnet insertion holeof the rotor coreexcept for a part of the magnet insertion holeof the rotor core, a cover partthat forms an inner area of the slitand covers at least a part of the magnet, and a convex partthat is protruded toward the positive Y-axis from the cover partand contacts the end part of the magneton the negative Y-axis side.

Accordingly, the magnetmay be held by the convex partof the first end plateand the convex partof the second end plateand fixed therein. Further, it is possible to communicate the slitof the first end plate, the gap G between the magnet insertion holeof the rotor coreand the magnet, and the slitof the second end platewith one another.

As shown in, the housinghouses the motor. For example, the inside of the housingis substantially sealed in a state in which the shaftof the rotoris made to pass through the end part of the housingon the negative Y-axis side. However, it is sufficient that the housinghouse at least the rotorof the motor, or may house anther drive transmission mechanism such as a clutch or a gear.

As shown in, the cooling mediumis housed inside the housing. The cooling mediummay be, for example, liquid such as oil used as a cooling medium. The cooling mediumenters the gap G between the magnet insertion holeof the rotor coreand the magnetvia the slitof the first end plateor the slitof the second end plate.

That is, the cooling mediumdirectly contacts the magnet. Accordingly, the magnetcan be efficiently cooled down by the cooling medium. Note that the cooling mediummay be circulated inside the housingby a pump (not shown). Further, the cooling mediummay be any medium that can enter the gap G between the magnet insertion holeof the rotor coreand the magnet, and may be, for example, gas.

Next, a method for manufacturing a rotor according to this embodiment will be described.is a cross-sectional view showing a state in which the first end plate is fixed to the rotor core.is a diagram showing a state in which the first end plate is fixed to the rotor core when seen from the positive Y-axis side.is a cross-sectional view showing a state in which the cover part of the first end plate is bent.shows a state in which the cover part of the first end plate is bent when seen from the positive Y-axis side.is a cross-sectional view showing a state in which the magnet is inserted into the magnet insertion hole of the rotor core.is a diagram showing a state in which the magnet is inserted into the magnet insertion hole of the rotor core when seen from the positive Y-axis side.

It is assumed that the slit, the cover part, and the convex partare formed in the first end platein advance and the slit, the cover part, and the convex partare formed in the second end platein advance.

First, the electromagnetic steel sheetsare laminated to form the rotor core. Then, as shown in, the first end plateis fixed to the end part of the rotor coreon the positive Y-axis side and the second end plateis fixed to the end part of the rotor coreon the negative Y-axis side.

Accordingly, as shown in, the whole area of the magnet insertion holeof the rotor coreis disposed in the first area ARwhen seen from the Y-axis direction. Further, as shown in, the whole area of the magnet insertion holeof the rotor coreis disposed in a third area ARsurrounded by an outer edge OEof the slitof the second end plateand a line Lthat connects end partsof the sliton the side of the opening.

At this time, when seen from the Y-axis direction, the magnet insertion holeof the rotor core, the slitof the first end plate, and the slitof the second end platemay partially overlap one another.

Next, as shown in, the cover partand the convex partare bent by the bending line Lof the first end platein the positive Y-axis side. Accordingly, as shown in, the magnet insertion holeis formed in an area surrounded by the outer edge OEof the slitof the first end plateand the bending line L.